Control mechanism for gun training apparatus



1947- L. s. LINDEROTH, JR 2,425,433

CONTROL MECHANISM FOR GUN TRAINING APPARATUS Filed Jan. 14, 1943 9 Sheets-'Sheet l 1947- L. s. LINDEROTH, JR 2,425,433

CONTROL MECHANISM FOR GUN TRAINING APPARATUS Filed Jan. 14, 1943 9 Sheets-Sheet 2 Aug. 12, 1947. 5, LJNDERQTHi JR 2,425,433

' CONTROL MECHANISM FOR GUN TRAINING APPARATUS Filed Jan. 14, 1943 9 Sheets-Sheet 3 Aug. 12, 194 L. s. LINDEROTH, JR

CONTROL MECHANISM FOR GUN TRAINING APPARATUS Filed Jan. 14, 1943 9 Sheets-Sheet 4 I. v Ill lLl V /64 a 24 0 I80 V206 u 259 755 P 246 5 I88 Aug. 12, 1947- L. s. LINDEROTH, JR 2,425,433

CONTROL MECHANISM FOR GUN TRAINING APPARATUS FilQd Jan. 14, 1943 9 Sheets-Sheet 5 200 l H 2 -5- 5f, 224

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CONTROL MECHANISM FOR TRAINING APPARATUS Filed Jan. 14, 1943 9 Sheets-$heet a 2 652 592 "'1 74 M 61/8 6M vW4 0590 0 W l T' J! {i i H )1; /56 fl-(0 I o F 5 we o W6 l w W I, o o w l. u T Q 1* my a 8 1947- v L. s. LINDEROTH, JR 2,425,433

CONTROL MECHANISM FOR GUN TRAINING APPARATUS Filed Jan. 14, 1943 9 Sheets-Sheet 7 Jaz- 574 558 M Z 5 456 5 I28 '66:? is; l 5 /2 606 L I v I Aug- 1947- L. s. LINDERQTHQJR CONTROL HBCBANISH FOR GUN TRAINING APPARATUS 9 Sheets-Shet 8 Filed Jan. 14, 1943 Aug. 12, 1947.

L. S. LINDEROTH, JR

CONTROL MECHANISM FOR GUN TRAINING APPARATUS 9 Sheets-Sheei 9 FilGd Jan. 14, 1943 Patented Aug. 12, 19 47 CONTROL MECHANISM FOR GUN TRAINING APPARATUS Lambert S. Linderoth, Jr., Marblehead, Mass., as-

signor to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application January 14, 1943, Serial No. 472,387

8 Claims.

This invention relaes to control mechanisms, and more particularly to mechanism for operating one or more control members, the movements of which effect the positioning of a movable device such as, for example, a gun, tool or like implement. The herein illustrated embodiments are shown as associated with the control members of .a power-operated gun training apparatus of the type disclosed, and claimed, in a copending application for United States Letters Patent, Serial No. 442,688, filed on May 12, 1942 issued October 8, 1946 as Patent No. 2,409,041, jointly by the present applicant and Fred V. Hart, but it is to be understood that, in its broader aspects, the invention is not limited in its applicability to that particular apparatus.

In the apparatus disclosed in the aforementioned application, the mechanism for controlling the operation of the gun training motors includes two control members the movements of which effeet a positioning of the guns in accordance with movements of a remotely located control handle, directly connected to said control members, so that the operator, by moving the control handle, is enabled to impose a space control on movements of the gun by the motors. This space control results from the action of follow-up mechanism associated with the movable control members and the motors, the arrangement being such that movements of these control members are exactly followed by the motors and, consequently, by the guns themselves which are driven thereby. A principal object of the present invention is to provide control mechanism for operating control members of this general type, i. e., members the movements of which effect a corresponding positioning of a device, so as to impose both a space and a rate control on the movements of a device. As used in this specification, and in the appended claims, the term space control means that movement of the controlling member a predetermined distance from neutral position results in a corresponding movement of the controlled member, i. e., the position in space of the controlled member is determined initially by the position of the controlling member. The term "rate control, on the other hand denotes a condition where a predetermined movement of the controlling member, from neutral position, effects a continuing movement of the controlled member at a rate determined by the displacement .of the controlling member from its neutral position. These are the meanings of these terms as understood in the art to which this invention relates.

With this purpose in view, the control mechanism of this invention is provided with a control handle for operating control members to impos a space control on their movements, and hence upon the positioning movements of a device controlled thereby, in accordance with the movement of the control handle; together with additional means for so moving the control members as to impose a rate control on their movements, and likewise on the positioning movements of the device, in accordance with the movement of the control handle. More particularly, movements of the control handle are transmitted to the control members, each of which is associated with a follow-up mechanism for controlling a fluid-pressure operated gun training motor, through a differential means. Preferably, and as shown in the herein illustrative embodiments of the invention, each differential means comprises a floating lever connected at an intermediate point to a control member, at one of its ends to the control handle and at its other end to a rate motor having a, controlling means operatively associated with the control handle. The arrangement is such that movement or the con trol handle first effects a corresponding initial displacement of one, or both, of the control members, thus imposing through the follow-up mechanism, or mechanisms, a space control on the positioning movement of the device by one, or both, of the gun training motors. This movement of the control handle operates the controllin means of one, or both, of the rate motors so that movement of the control member, or members, is thereafter continued at a speed dependent upon the extent of initial movement of the control handle and a rate control is thus imposed on the movements of the control member. Inasmuch as movements of the control members are followed exactly by the movements of the gun, movement of the control handle will, therefore, impose a corresponding rate control on the positioning movements of the gun.

Preferably, and as herein shown, the rate motors are fluid-pressure operated and each controlling means therefor comprises a valve having a valve member movable from a closed position to control the flow of pressure fluid to, and ex-- haust from, opposite sides of its associatedmotor. Means are also, provided for rapidly reciprocating the movable valve member, equal distances in opposite directions from its closed position, so as to apply a. series of balanced pressure impulses alternately to opposite sides of the motor, together with means for changing the posi- 3 tion of these reclprocations with respect to the closed position, by movement of the control handle, for the purpose of selectively unbalanein the pressure impulses on one side or the other of the motor and thereby controlling the direction and speed of operation of the motor. As a result static friction in the rate control valves, and also throughout the whole system, is eliminated and a very accurate and smooth controlling action is obtained.

The above, and other, objects and featuresof this invention 'will appear in the following detailed description of the illustrative embodiments thereof shown in the accompanying drawings, and will be pointed out in the claims.

In the drawings,

Fig. 1 is a view in side elevation of gun training apparatus embodying this invention;

Fig. 2 is a view in front elevation of a part of the apparatus shown in Fig. 1;

Fig. 3 is a view, partly in section on line III-III of Fig. 2, looking in the direction of the arrows, of the elevating motor oi the apparatus;

Fig. #1 is a plan view of the apparatus shown in Fig. 1 taken below the guns themselves;

Fig. 5 is a plan view of the azimuth motor;

Fig. 6 is a sectional view of one of the space control valves;

Fig. 7 is a view of the control handle and associated parts as viewed from the lei't in Fig. 1;

Fig. 8 is a sectional view of one of the rate control valves taken on line VIlI--V'1II of Fig. 7 and looking in the direction of the arrows;

Figs. 9 and 10 are schematic views of the elevation and azimuth control mechanisms respectively;

Fig. 11 is a view in side elevation, with some parts in section, of a modified form of control mechanism embodying the invention;

Fig. 121s a view in end elevation of the control mechanism shown in Fig. 11, looking in the direction of the arrow II, with parts of the casing broken away to expose elements contained therein;

Fig. 13 is a plan view of the control mechanism' shown in Fig. 11 taken from about the level indicated by line IK|I[XI1I in Fig. 12 and looking down in the direction of the arrows;

Fig. 14 is a sectional view, taken on the line XIV-XIV of Fig. 13 and looking in the direction of the arrows. of part 01' the control mechanism;

Fig. 15 is a detail view of another part of the control mechanism as viewed from a plane indicated by lines XV-XV and looking in the direction of the arrows;

Fig. 16 is a sectional view of one of the rate control valves used in the modified control mechanism;

Fig. 1'7 is 'a plan view of a sleeve assembly forming part of the valve shown in Fig. 16; and

Fig. 18 is a schematic view of a modified control mechanism shown in Figs. 11-13, inclusive.

The herein illustrated embodiments of the invention are, as above-indicated, disclosed as applied to power-operated apparatus for training two machine guns mounted in an airplane. The means for mounting the two guns for universal movement about two axes at right angles to each other, the power-operated apparatus'for training the guns, by swinging them about these axes, the mounting of the associated sight, and the linkages for maintaining the optical axis of the sight parallel with the guns are essentially the same as those disclosed in, the afolsillqiiioned copending application.

aseaess rotatably mounted in a bearing 32 which is carthrough the adapter bars SI of each gun assem- Referring to Figs. 1 and 2, the two guns G, G are mounted for universal movement inside of the fuselage F of an airplane so as to project through an opening 0 therein in the following manner. Extending upwardly from a plate 20, secured to a cross-member 2| of the fuselage structure, are two posts 22 on each of which there is rotatably mounted a sleeve 24. Pinned to the top of each sleeve is a block 26 which carries two side plates 28 Joined at their upper ends by a second block 30. Each of the blocks 30 is fied by a. plate 33 secured to an upper crossmember 34. Clamped to the lower ends of the sleeves 24 are two arms 38 and Il (Fig. 5) joined by a cross-link 40. The blocks II are likewise connected by a cross-link ll (Fig. 2). plates are each provided with forwardly extending cars 42 andpivoted to each of these cars, on a pin 4', is one end of an arm ll. Each of the two guns is mounted on, and between, two of these arms by means of bolts 48 passing bly, extended bearing portions 52 of the arms and clamping plates SI.

Secured to the opposite end of each arm 44 is a downwardly extending strap 58 and each pair of these straps is connected to a slide 8 mounted on the sleeve 24 and held against rotation with respect thereto by means of a key ll. These two slides are rotatably connected to the opposite ends of a yoke member 8!, which is itself secured to a crosshead ll slidably mounted on the exterior of a cylinder It, by means of collars 6|, positioned between thrust flanges l3, 8 on the slides, Figs. 1 and 2. As will be apparent, vertical movement of the crosshead will swing the two glms together about the horizontal axis provided by the pins ll while movement of the arm 36 (Fix.

.5) will swing the guns about the vertical axes provided by the posts 22 and bearings 12. During these training movements the two guns will be maintained in parallelism by means of the yoke 02 and crosslinks 4| and ll, as will be readily understood.

These training movements are effected by means of two fluid-pressure motors, the one for swinging the guns about their horizontal axes, hereinafter referred to as the elevation motor, comprising a piston ii, in cylinder 88, which is connected to the crosshead 64 by means of a piston rod I0 (Fig. 3). The motor for swinging the guns about their vertical axes, hereinafter called the azimuth motor, comprises a cylinder 12, pivoted to a bracket member 14 mounted on the plate 20, and a piston 18 which is connected to the arm 36 by means of a piston rod ll (Fig. 5). Referring to Figs. 9 and 10, in which these motors and their controlling valves are shown schematically, cylinder 12 is connected to a reversing valve 80 by pipes 82, 84 while cylinder I8 is connected to a similar reversing valve 9! by pipes 8', Il, each of these valves being connected to a source of pressure fluid (not shown) and to exhaust by means of pipes 02, 94.

The valves I. and SI each have a movable valve member 96, provided with an operating rod ll, projecting from the valve housing as shown, Figs. 6, 9 and 10, and slidably mounted within a sleeve III! held in the housing by means of threaded thim-bles Hi2, IN. This sleeve is provided with spaced grooves I", Ill and I (Fig. 6) connected to exhaust line ll, to pipes 82 and II, and

member has two enlarged portions III and Ill The side each just wide enough to cover a ve I08. Accordingly, and as will be readily understood by persons skilled in the art, movement of the reversing valve member to th right or left of the neutral position in which it is shown will result in admission of pressure fluid to one or the other end of the associated motor and exhaust the other end, exhaust grooves I06 being connected by a duct H6 in the housing, as shown.

Pivoted to the rod 98. of the valve 80, is a floating lever I20, and a similar floating lever I22 is likewise pivoted On the rod 98 of valve 90,. At one end, the lever I20 is connected to a valve operating lever I24 by a link I26 and, at its pp site end, this lever is connected, by a link I29, to the arm 36 (see Figs. 2, 4 and Likewise, one end of lever I22 is connected to another valve operating lever I28, by means of links I30, I32 and bell crank I34, while its opposite end is connected to the crosshead 64 by a link I36 (see Figs. 3, 4 and 9). Referring to Figs. 1 and-1, the valve operating levers I24 and I28 are fulcrumed in bearings on a plate I38 which is secured to a cross-member I40 of the airplane. This plate is of considerable width so that these arms are located on the opposite sides, and extend rearwardly, of an armored wall I42 which stepmthe gunners compartment from the spac occupied by the guns.

By connecting the valve operating levers to their associated valve operating rods by means of floating or difierential levers, as above described, a follow-up or servo action is 0 That is, movement of either of the valve operating levers, as for example, the lever I24, will swing the lever I about its point of attachment to the link I29 and, through rod 98, will shift the valve member 96, thus causing the piston I6 to swing the arms 36 and 38 in one direction or the other. This movement of the arm 36, however, will immediately swing the lever I20 in the opposite direction and return the valve member to closed p ition. The operation of valve operating lever I28 to control piston 68 is the same and thus the direction and extent of each motor is determined by the direction and extent of movement of its associated valve operating lever. The arrangement is such that movement of the lower ends of levers I24 and I28, as viewed in Figs. 9 and 10, to the right or left and up or down, respectively, as indicated by legends thereon, will cause the pistons 68 and I6 to impart corresponding training movements to the guns in azimuth and elevation. The speed of movement of each motor is likewis determined by the speed of movement of its associated valve operating lever since, as will be apparent, the displacement of the valve operating rod, at any instant. and hence the valve opening, will depend upon the amount that movement of the operating lever is kept ahead of the movement of the motor piston. The levers I24 and I28 thusfunction as control members, the movements of which effect the positioning of the guns, in the same manner as the two bell-crank levers I36 and I49 provided in the apparatus disclosed in the above mentioned application. Adjustable stops I44 (Fig. 4) are provided for each rod 98 for limiting the maximum speed of training movement as desired.

A sighting device S (Fig. l) is pivotally mounted adjacent to a window W, and above the gun, on a yoke I46 arranged for turning movflnent relative to a fixed part I48 of the plane. The optical axis of the sighting device is maintained parallel to the axes of the guns by means of the Ill following connections. Link I50 connects one end of a. lever I52 to a rod I54 secured to the crosshead 64 and guided in a bearing bracket I56. The other end of this lever is connected to a rod I58, the vertical displacement of which, through hell crank I60, link I62 and arm I64, swings the sight about its horizontal axis. The yoke I46, and with it the sight, is swlmg about a. vertical axis, by means of a link I66 extending between anarm I68 on the yoke and an arm "0 carried by a. shaft "2 secured to one of the blocks 30,

The apparatus so far described is substantially the same 8s that disclosed in the above-menfinned application, to which reference may be made for a more detailed description of certain of the parts and a fuller explanation of the mode of operation, and provides mechanism for obtaining a space control of the operation of a plurality of power-operated means for training a gun. In the apparatus disclosed in said prior application, direct mechanical connections from a single control handle to the two bell-crank levers, which, as noted above, corre ond in function to the levers I24 and I28, are provided and space control of the training movements of the guns about two axes at right angles toeach other is thus obtained,

For moving the two valve operating levers I24 and I28 by means of a single control member, and in such a manner as also to obtain a rate control of the gun training movements, the following mechanism is provided; The single control member comprises hand grips I joined by a crossbar I82 and mounted for pivotal movement on a shaft I84 carried by upstanding portions I86 of a cylindrical member I88 (see Figs. 1, 4, 7, 9 and 10). The member I88 is rotatably mounted in a hearing portion I90 of a supporting frame I92 and has a downwardly and forwardly extending arm I94 and a laterally projecting arm I96. Extending laterally, from opposite sides of the frame, are two rods I98, 200, on which are mounted sliding blocks 202, 204 (Figs. 4, 9 and 10). The arms I86 are offset from the vertical axis of member I88 and secured to the shaft I84 is an am 206. Also mounted on the frame are two fluid pressure motors 208, 2I0 comprising cylinders 2I2, 2I4, pistons 2I6, 2I8 and piston rods 220, 222, respectively (figs. 9 and 10) Pivoted at one end to the block 202 is a floating or dlfierential lever 224, the opposite end of which is forked to embrac a pin 226 carried by the piston rod 222 of motor m, and, at about its mid point this lever is connected to the valve operating lever I28 by means of an adjustable link 228. As has previously been explained, movement of the lever I28 controls the operation of the gun elevating motor, comprising piston 68 and cylinder 66, with a, follow-up or servo action, and this lever will hence be referred to as the elevating servo lever to it from the other valve operating lever I 24 which will be called the azimuth servo lever, since it controls the operation of the azimuth motor, comprising piston 16 and cylinder I2.

The arm 206 is connected to the block 202, by means of links 230, 232 and a bell crank 234, mounted on frame I92, so that rocking movement of the shaft I84, by handle I80, will shift this block along the rod I98, and, through lever 224 and link 228, will move the elevating servo lever I28, thus efl'ecting an initial displacement of the gun by the elevating motor. This initial displacement of the block 202 and lever I28 will correne ates spond in speed, direction and seem to the speed,

direction and extent of rocking movement of the handles 988, as will be apparent from the movement of the guns about their horizontal axes. Thus, movement of the handles I88, in the first instance, effects a corresponding displacement of the lever I 28 which imposes a space control on the movements of the gun by the elevating motor.

Rate control of the displacement of the lever I28, and on the operation of its associated elevating motor, is obtained in the following manner by the motor 2I8, which will be referred to herein: after as the elevation rate motor. Also mounted on the frame I92 is a reversing rate valve 238 which is connected to the source of pressure fluid (not shown) by a pipe 238 and to exhaust by a pipe 248. The valve has two outlets 242, 244 which are connected to opposite ends of the cylinder 2. by pipes 243, 245, and a movable valve member 248 for controlling the direction and rate of the ilow of pressure fluid to and exhaust from the motor 2I8. Movement of the handles I88 is transmitted to the movable valve member by means of an arm 248 and a link 258, connecting the arm to the bell crank 234, and. the arrangement is such that, when the handles are moved, in either direction, the valve member I 248 is shifted from the neutral postion, in which it is shown in Fig. 9, to start the rate motor 2 I 8 in operation. For example, if the handles are rocked a predetermined amount in a clockwise direction (Fig, 9), valve member 248 will be shifted to the right and pressure fluid will b admitted to the right-hand end of cylinder 2I4 and exhausted from the left-hand end. This will cause piston 2 I8 to move to the left, carrying with it piston rod 222 and the lower end of the differential lever 224, at a rate dependent upon the amount of displacement of the valve member which, in turn, is determined by the amount of angular movement which was imparted to the handles initially. The block 282 being held fixed, by the connections back to the handle when movement of the handles is stopped, this movement of the lower end, as viewed in Fi 9. of the differential lever will continue the movement of the elevating servo lever I28 in th same direction in which it was initially displaced by the lateral shifting of the block 282 to the left that, in the first instance, was effected by the angular displacement of the handles. Also, the stopping of movement of the handles will hold the rate valve open so that the rate of movement of the lower end of the diflerential lever and of the servo lever I28 will be determined by the amount of handle displacement.

If the handles are moved counterclockwise the same results will be obtained with the directions of movement of the parts reversed. The range of movement of lever I28 is limited by stops 252, 254, formed on a block 258 flxed to the rod I98, and, when the lever engages either oi. these stops, the continued operation of the rate motor will brin the handles back to their original position and. at the same time, return the valv member 248 to neutral position, thus' stoppin the rate motor. These stops, as well as similar stops 253, 255, on a block 251, associated with the traversing servo lever I24, are so arranged that movements of the gun in both elevation and azimuth are kept with- 8 in desired limits. Auxiliary safety stops 2 and 288 '(Figs. 4, '1 and 9) are also provided for limitmg the'movem ents of the handles i88. From the foregoing it will be seen that by swinging the handles I88, in a vertical plane about the axes provided by shaft I84, the operator is able to impose both a space and a. rat control on the operation of the elevating motor and, as a consequence of this, on the elevating movements of the guns about the axes of pins 48.

7 Similar mechanism is also provided for con-- trolling movements of the gun in azimuth. The

arm I94 is connected, through a link 288, to the block 204 (Figs. 7, 4 and 10), and movements of this block by the handles are transmitted to the servo lever I24 by a differential lever 282, pivoted at one end to the block and having its opposite end forked to embrace a pin 284 in the piston rod 228 of the azimuth rate motor 288, and a link 288. The operation of this motor is controlled by a rate valve 288 which is exactly like rate valve 238, having outlet ports 242, 244, connected to the opposite ends of cylinder 2I2 of azimuth rate motor 288, by pipes 243, 245, and to the source of pressure fluid (not shown) and to exhaust, by pipes 238 and 248, respectively. This valve also has a shiftable valve member 248 which is operated by an arm 214, in a manner which will be described below. This arm is connected to the arm I98 by a link 218. Accordingly, when the handles I88 are swung either to the right or to the left the lever I24 is initially displaced a corresponding amount and, at the same time, the rate motor is started to continue movement of the lever at a rate determined by the initial movement of the handles.

The two rate valves are exactly alike and similar reference characters have been applied to the like parts of each valve. Referring to Fig. 8, in which one of these valves is shown in section. the casing is provided with a longitudinal bore 288 in which an inner sleeve 282 and an outer sleeve 284 are positioned by means of threaded thimbles 288, 288. The movable valve member 248 is slidable axially in the inner sleeve, on piston portions 298, 292, 294, 298, by means of a nut 288, to which either the operating arm 248 or 214 is clamped. This nut is rotatably mounted on an extension 38I on one end of the member 248, between flange 383 and a nut 388, and has threads 382 engaging a threaded portion 384 on the thimble 288. Rotation of the nut 298 will translate the valve member axially in the sleeve 282. In Figs. 9 and 10 this action is schematically illustrated as a direct reciprocation by the arms 248 and 214 which are there shown as pivoted to the frame I42. Seals 388 surround the extension 38I and a similar extension 383 on the opposite end of the member 248. The inner sleeve is formed'in three sections which, when assembled in the housing, provide five axially spaced external grooves 3I8, 3I2, 3I4, 3I8, 3I8 that communicate directly with five similar external grooves 328, 322, 324, 328, 328, formed on the exterior of the outer sleeve 284. The inner sleeve also has two internal grooves 338, 332 and between each of these grooves and its associated external groove 3I2 or 3I8 there is a slot 334,

out before the three sections were assembled.

The other external grooves 3I8, 3 and 3I8 communicate directly with the interior of the sleeve and the spaces between the piston portions 288, 292, 294 and 298. The piston portions 292 and 294 are so spaced that their facing edges just cover the internal grooves 338, 332, when the valve member is in the neutral position shown, and are traversed by narrow, gradually shallowing, kerfs 336 which emerg back of the facing edges of the piston portions at distances just equal to the width of the grooves 330, 332.

Grooves 322, 326 are connected to the pipes 243 and 245, leading to the rate motor to be controlled by the valve through the openings 242' and 244, respectively, groove 324 i connected to the pressure line 238 and grooves 320, 328 to the exhaust line 240. In the illustrated construction, the connection of groove 320 to exhaust is by way of an axial and two radial ducts 340, 342, 344 in the valve member 246, this construction being such that a separate exhaust connection, communicating with groove 320, could be provided on the housing, if desired.

When either of the valve members 246 is displaced from the neutral position shown (Fig. 8), say upwardly, for example, the piston portion 292 will uncover the groove 330 and slot 334, associated with the groove 3I2, and pressure fiuid will flow, through this slot, groove'3l2 and groove 322, pipe 243, to one end of the motor cylinder. At the same time, kerf 336 on piston 294 will overlap groove 322 so that pressure fluid, from the opposite end of the motor cylinder, can flow from pipe 245 through groove 326, groove 3I6, slot 334, groove 332, kerf 336, and grooves 3I8 and 328, to exhaust pipe 240. The efiective area of the opening provided by the kerf 334 from groove 332 varies directly with the amount of displacement of the valve member and thus meters the flow of pressure fluid to exhaust, this metering efiect continuing, as the displacement of the valve member increases. There being a closed circuit between the opposite ends of the motor and the valve it will be obvious that the speed of operation of the motor piston will be determined by the rate of flow of pressure fluid from the motor to exhaust. The area of each slot 334 is greater than the maximum effective area of its associated kerf 338 so that the latter always determines the speed of operation of the motor. Since the effective area of the kerfs 336 depends upon the amount of displacement of the valve member from neutral position it follows that the speed of operation of the rate motor is proportional to the amount of movement of the control handles.

In operating the apparatus to aim the guns at a moving target, the gunner grasps the handles I80 and observes the target through window W. Assuming, for example, that the guns are in the position shown in Fig. 1 and that a, target is observed above and to the left of the direction in which the guns, and also sight S, are pointing, to bring the guns quickly to a position in which they will point toward the target, the gunner swings the handles down and to the right. This causes the gun training motors to move the guns so that their back ends, which are nearest the gunner (Fig. 1), are likewise moved down and to the right, by the space control that is thus imposed on the motors by this initial movement of the handles, and the guns pointed generally toward the target. It will be noted that this movement of the handles corresponds in direction to that which the gunner would impose on the gun themselves if he were moving them directly by their hand grips H.

If this initial movement of the handles has been properly gaged, the target will be within the field of view of the sighting device, which, of course, has followed the movement of the 406, 4I0 and 408, M2, respectively.-

guns, but to one side or the other, and above or below, the crosshairs or reticle of the sight. The target will also appear to be moving across the field of view of the sight in a direction and at a speed which will depend on the relative speeds or the target and the gunner's airplane, the angle between their lines of flight, and also the angular rate of movement of the guns under the rate control which is now being imposed on the gun training motors by the rate motors. As a result, the target will seem to be either coming into closer alinement with the optical axis of the sight or departing from such allnement. In the former case, the gunner will gradually decrease the rate or movement 01 the gun by moving the handles back toward their original position an amount sufiicient to match their rate with the target rate at the instant the line of sight of the sight, and also the line of fire of the guns, intersect the line of movement of start to move away on the opposite side. This will be immediately corrected by a return movement of the handles, in the original direction, which not only speeds the time up, by the change in the speed of operation of the rate motors and the resulting rate control function, but also bodily shifts them back toward the target by the space control function.

On the other hand, the target, when it is first picked up in the sight, may appear to be moving away from a position of alinement with the optical axis of the sight. In this case the handles are given a further displacement, in the original direction, which bodily moves the guns, space control, toward the target, and, at the same time, increases the speed of movement of the guns, rate control, eventually bringing'the line of sight, and line of fire, on the line of movement of the target, with the guns movin at a rate to track and keep on the target.

These movements of the handles first to bring the guns approximately on the target and then to adjust the rate of movement of the guns so as to track the target are made automatically by the gunner as he observes the target through the sighting device, the combination of space and rate control affording an aided tracking function making it possible for the gunner quickly to get on the target, closely to track the target, and also easily to follow changes in the speed and/or direction of movement of the target by slight movements of the control handle.

In Figs 11 to 18 a modified form of control mechanism for operating the servo levers I24, I28

is shown. This mechanism is contained within a compact housing 400 which is adapted to be mounted in the gunners compartment C just in back of the armored wall I42 and between the rearward portions of the two servo levers. The housing has top and bottom walls 402, 404, connected by vertically extending post members 406, 408, M0, and M2, the openings between these post members being closed by removable cover plates 4I4 (Figs. 11 and 13), and cross members M6, M8 extending between the post members The control handles 420 are pivotally mounted on the outside of two rearwardly and upwardly 836 which is connected to one end of a diiierential lever 638. The opposite end of this difl'erential lever is connected to an arm 639 extending downwardly from a hub 640 which is also journaled on the shaft 628. This hub has a second arm 842 in which a pin 544 is mounted and. adjacent thereto on the shaft, there is secured a collar 646 having a flange 648 provided with an car 650. Wrapped around the shaft and having one end anchored thereto is a torsion spring 652 the opposite end of which is secured to a pin 654 in a disk 658 which is rotatably molmted on the shaft. This disk has an ear 558 and is positioned adjacent to the hub portion 650 of an arm 662 on which there is mounted a pin 664. The pins 844 and 664 engage the ears 65d and 658 in the same manner as pins 516 and 518 engage ears 566, 514 in the yieldable coupling shown in Fig. 14, and so that angular movement of the arm 652 will be transmitted to the arm 642, and thence to am 639, through spring 652. In Fig. 18 these yieldable couplings have been omitted and the arms 552, 590 and 639 and 662 represented as being formed integrally as bell-crank levers and in fact these parts could be so constructed, if desired.' However, by providing these yieldahle couplings, the danger of damaging the parts should the servo levers I24 or I28 become jammed is avoided. The arm B52 is connected to the pi:

ton rod 452 of the azimuth rate motor by means of a, sliding block 666 and pin 568 and a link 610 extends between the midportion of the diiierential lever 638 and servo lever I24. The upstanding lever 624 is also connected, by link 612, to one arm of a valve operating bell crank 614 the other arm of which is connected, by a link 616, to a second vibrating or dithering lever 618. This mechanism operates to impose space and rate control on the movements of the servo lever I24, which correspond in speed, direction and extent to movements of the control handles, and hence upon the operation of the azimuth motor in the same manner as such control is imposed on the elevating motor by the mechanism just described above.

Returning now to the manner in which the rate control valves operate and referring to Figs. 12, 13 and 18, the two bell cranks 604 and 614, by means of which movements of the control handles are imparted to the valves, are each pivoted on a post 688 having a base 682 that is clamped to the upper ends of the two valve sleeves 460. The vibrating or dithering levers Sid and 518 are pivotally connected to the stems 528, 530 of the two valve members 522 and also to a crosshead 884 (Fig. 13). This crosshead is connected to an eccentric 686 by means of a. connecting rod 588 and slide 890. The eccentric is rotated at a high rate of speed by a motor 692 so that the right-hand ends of the levers Gill and 618 are vibrated at a very rapid rate.

When the control handles are in neutral position, as shown in Figs. 11 and 18, the bell crank levers 604 and 614 will occupy the positions in which they appear in Figs. 12 and 18 and, as a. result of the above vibrating movements which are imparted to one end of these levers. the other end being held fixed, the valve member operating rods will be reciprocated back and forth from mid-position. In Fig. 16 the valve member 522 is shown at one extremity of its reciprocation in which position the slit l8 is imcovered a small amount on the exhaust side of the piston portion 524 while slit 520 is lmcovered an equal amount on the pressure side of piston portion 526. Fig. 18 shows both valve members 522 in this position. As the eccentric 688 rotates a half turn, the valve members will be displaced equal distances on the opposite sides of their midpositions so that ports Eli! are connected to pressure while ports 520 are connected to exhaust. As a result of this rapid reciprocating or dithering" of the valve members the opposite faces of the pistons 442 and 448 will be subjected to a series of very short pressure impulses, of equal duration and strength, the eflects of which are balanced so that no appreciable movement of either piston is produced.

considering now one of these valves, for example, the elevation valve which is operated by lever BIO, it the left-hand end of this lever, which is connected to the bell crank 604 by link 608, is elevated slightly, by counterclockwise movement of the handle 420 as viewed in Fig. 18, the reciprocations of the valve member will be transferred to a locality nearer to the top of the valve housing. Now the duration and extent of the uncovering of the port 5!!! to exhaust will be decreased while the duration and extent of its uncovering to presure will be increased. Likewise, the duration and ment of the uncovering of port 520 to exhaust will be increased while the duration and extent of its uncovering will be decreased. As a result of this, the pressure impulses which are imposed onthe opposite sides of piston 442 will be unbalanced, those on the bottom face, as viewed in Fig. 18, now being stronger, due to the greater extent of the opening of port SIB to pressure than to exhaust and the correspondingly lesser extent of the opening of port 520 to pressure than to exhaust, and longer, due to the greater duration of the opening of this port to pressure than to exhaust, and the correspondingly lesser duration of the opening of port 520- to pressure than to exhaust. This unbalancing of the pressure impulses will cause piston 442 to move upwardk at a speed dependent upon the net difierence between the impulses on its opposite faces. As will be apparent this difference will, in turn, depend upon the amount the left-hand end of the lever BIB was displaced, by movement of the control handle, from the position shown in Fig.

18. A similar result, in the opposite sense, will, of course, be produced by a downward displacement of the right-hand end of lever BIO by a clockwise movement of the control handle. Likewise, the operating lever 618 may be manipulated, by swinging the control handles to the right or left, to change the locality of the reciprocations of the valve member 522 of the azimuth rate valve.

Thme rate valves of the modified form of my invention hence operate like the rate valves of the first described embodiment to control the operation of the rate motors in accordance with the direction and extent of displacement of the control handles from neutral position. For satisfactory results the change in the speed of operation of the rate motors must be very accurately controlled and, under most conditions, the amolmt of change, at least for small movements of the control handles, is very small. As explained above, the desired accuracy and sensitivity of rate valve action is obtained in the valves employed in the first described embodiment by means of the exhaust control kerfs 336. This construction, however, requires very accurate machining and the narrow kerfs are quite likely to become fouled with sediment if used in systems in which proper filters are not provided.

The dither valve construction just described, and which is shown embodied in the modified form of the invention, not only avoids the aforementioned disadvantages but also provides improved operating characteristics, as will now be explained. As will be apparent from the manner in which the dither valve operates, a unit displacement of the left-hand end of a valve operating lever (Fig. 12) will produce a change in the rate of flow of pressure fluid which is equal to one-half of thechange in rate of flow that would be obtained for the same displacement if the valve member were not being dithered. This is because of the fact that the dithering action keeps the valve closed for one-half of the time and open for the other half. Thus the effective valve opening is only one-half of the actual and the sensitivity of the valve is doubled. Likewise, with the square ended slits l8, 520 and straight sided piston portions 524, 526, which are relatively easy to machine accurately, and the dithering action of the valve member, a very accurate control over the rate of flow of pressure fluid through the valve is obtained since this rate is absolutely dependent upon the amount of displacement of the valve operating lever.

In valves in which the rate of flow depends in part on the shape of inlet or outlet ports, as for example the kerfs 336 in the valve piston portions of the valve member in the first described rate control valves, any inaccuracy in the machining of such ports will be reflected in the operation of the valve. Also, unless these ports, as well as the Valve ope'rating member, are very accurately machined, there is likely to be a dead spot, 1. e., small range of movement of the valve member with no resultant port opening, or a leakage through the valve, to one end or the other of the motor cylinders, when the valve member is in mid-position. Since the slightest displacement of the valve operating lever will, as has been already explained, result in an unbalancing of the pressure impulses, there is, practically at least, no such dead spot in the dither valve.

Furthermore, with the valve member continuously in motion there is no static friction, between the valve member and valve, to be overcome by the operator when he moves the control handles. Jerky motion of the control handles, which may be caused by static friction in the rate control valve is therefore avoided and a very smooth action obtained. Also, static friction in the rate motors, and in fact throughout the whole fluid-pressure system, is eliminated as a result of the action of the dither valves. The rapid application of pressure impulses alternately to the opposite sides of the rate motor pistons keeps these pistons always mobile and in a state of vibration, although the extent of movement is so slight as to be practically imperceptible. Accordingly, the static friction, between the pistons and their cylinders, is broken and these pistons are free to respond at once and to move in either direction when these impulses are unbalanced by the slightest movement of the control handle. Since the rate pistons are connected to the servo levers, which control the flow of pressure fluid to the elevation and azimuth motors, this effect is transmitted to the servo valves and, ultimately, to the pistons of the gun training motors,

Having thus described my invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. Control mechanism for power-operated guntraining apparatus having a gun to be trained, a

motor for training the gun and control means therefor including a member movable from a neutral position to determine the direction, speed and extent of movement or the gun by the motor, said mechanism comprising 'a manually shiftable member, movable at will by the operator, for selectively displacing th movable member from its neutral position to cause said motor to impart a corresponding training movement to the gun, and power-operated means under the control of said shiftable member for continuing the movement of said control member to cause the motor to continue the training movement of the gun at a rate dependent upon the extent of the initial movement of said shiftable member by the operator.

2, Control mechanism for power-operated guntraining apparatus having a gun mounted for trainin movements, a plurality of motors for moving the gun in difierent planes and separate control members, movable in opposite directions from neutral positions for determining the direction, speed and extent of training movement of the gun by each of said motors, said mechanism comprising a manually shiftable member movable by the operator in a plurality of planes corresponding to the different planes of training movement of the gun by said motors for selectively displacing said control members from their neutral positions to cause said motors to impart a corresponding training movement to said gun, and means operable in response to movement of said shiftable member for continuing movement of the control members to efiect a continued trainto determine the direction, speed and extent of training movement of the gun by the motor, said mechanism comprising a manually shiftable member, movable at will by the operator, for selectively displacing said valve-operating memberfrom its neutral position to cause said member to impart a corresponding training movement to the gun, and fluid-pressure-operated means under the control of said shiftable member for continuing the movement of the valve-operated mem-- her to cause said fluid-pressure motor to continue its training movement of the gun at a rate dependent upon the extent of the initial movement of the shiftable member by the operator.

4. Control mechanism for power -operated guntraining apparatus having a gun mounted for training movements, a plurality of fluid-pressure motors for training the gun in difierent planes,

separate control valves for said motors, each insure-operated means operable in response to movement of said shiftable member for continuing the movement of the valve-operating members to efiect a continued training movement of the gun in the same direction and at a rate dependent upon the extent of the initial movement of said shiftable member by the operator,

5. Control mechanism for operating a plurality of members each movable in opposite directions from a, neutral position to determine the direction, speed and extent of movement of one of a plurality of motors, comprising a plurality of differential means each having an output element associated with one of said movable members and two input elements, a single control handle connected to one of the input elements of each differential means, a plurality of auxiliary motors each connected to the other input element of one of said difierential means, and means for controlling the direction and speed of movement of said auxiliary motors in accordance with the direction and extent of movement of the control handle.

6. Control mechanism for operating a plurality of members each of which is movable in opposite directions from a neutralposition to determine the direction, speed and extent of movement of a device in a particular plane, comprising a plurality of difierential means each having an output element associated with one of said movable members and two input elements, a single control handle connected to one of the input elements or each diflerential means, a plurality of auxiliary motors each connected to the other input element of one of said difierential means, and means for controlling the direction and speed of movement of said auxiliary motors in accordance with the direction and extent of movement of the control handle by the operator.

7. Control mechanism for operating a plurality of members each movable in opposite directions from a neutral position to determine the direction, speed and extent of movement of one of a plurality of motors, comprising a plurality of differential means each having an output element associated with one of said movable members and two input elements, a single control handle connected to one of the input elements of each differential means, a plurality of fluidpressure motors each connected to the other input element of one of said diflerential means, and valve means for controlling the direction and speed of movement of said fluid-pressure motors in accordance with the direction and extent or movement of the control handle by the operator.

8. Control mechanism for operating a member movable in opposite directions from a neutral position, comprising a control handle, a fluid-pressure motor and differential means for transmitting movements of the handle and of the motor to said member. a valve having a valve member shiftable from a closed position for con- I trolling the flow of pressure fluid to and exhaust from the opposite sides of the motor to control the direction and speed of its movements, a lever for operating said valve member, means for vibrating one end of said lever for rapidly reciprocating said valve member, equally on opposite sides of its closed position, to connect both sides of the motor alternately to pressure and exhaust, and means for positioning the other end of said lever, in accordance with movements of the control handle, thereby to change the position of said reciprocations and control the direction and speed of operation of said motor by varying the rate of flow of pressure fluid to and exhaust from opposite sides thereof.

LAMBERT S. LINDEROTH, JR.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,387,678 Anderson Aug. 16, 1921 2,047,922 Seligman July 14, 1936 695,061 Lang Mar. -11, 1902 2,082,410 McCauley June 1, 1937 1,530,445 Warren Mar. 17, 1925 1,638,102 Roucka Aug. 9, 1927 559,904 Pfatischer May 12, 1896 1,470,369 Kaminski Oct. 9, 1923 2,347,368 Rosen Apr. 25, 1944 2,071,424 Papello Feb. 23, 1937 1,360,664 Miller Nov. 30, 1920 2,388,010 Pohl Oct. 30, 1945 2,284,611 Barnhart May 26, 1942 FOREIGN PATENTS Number Country Date 350,955 Great Britain June 11, 1931 422,009 Great Britain Jan. 3,1935

489,208 Great Britain July 21, 1938 789,778 France Aug. 26, 1935 371,517 Great Britain 1931 292.085 Germany 1916 440,342 Great Britain 1935 673,342 France Oct. 7,1929 

